Collet chuck



Aug. 11, 1931. G. M. cLAss 1,818,305

COLLET CHUCK Filed Dec. '16, 1929 2 Sheets-Sheet 1 Aug. 11, 1931. CLASS 1,818,305

GOLLET CHUCK Filed Dec. 16; 1929 2 Sheets-Sheet 2 1': I I I Patented Au .11, 193i :NITEDT'STATES PATENT OFFICE enonen m. crass, or. MADISON, Wisconsin, ASSIGNOB TO srsnomimlacfimn oom- PANY, or mamson, WISCONSIN, A conronarron or Wiscons n eoLLn'r cnncx Application med December 16, 1929., SerialNo. 414,203.

This invention relates to collet chucks,

and has reference more particularly to achuck for use on turretlathes in which turn ing operations are to be'performed onbar stock. The chuck is of the split collet type, in which the collet is compressed to grip the work by means of a sliding collet closing ring with a taper bore fitting a correspondingly tapered surface on the collet, the sliding ring being given an endwise movement by means of a hand lever.

One common method for giving the proper sliding movement to the collet closing ring is by the use of a push tube extending through the hollow spindle and surrounding the work, the same being connected to a lever at the. rear end of the lathe spindle. Another method is to operate the collet closing ring by a lever attached to the front 530 end of the headstock. The latter method is employed in connection with the device of y back plate which isscrewed onto the for-- the present invention.

In the usual collet chuck of this class the gripping of the Work is accomplished direct- 5 1y by the movement of the lever and is a positive operation, while the ungripping is not a positive operation, the automatic expanding tendency of the collet being relied upon to release the work. This is unre so liable, because the-frictionabetween the tapered surfaces of the collet and the collet closing ring may be so excessive as to overcome the automatic expanding tendency of the collet, and thus create difiiculty' in unchucking the work. The main feature of the present invention resides in an improved -means for positively actuating the collet closing ring in both directions, whereby both the chucking and unchucking operations are manually performed. I

One simple and practical embodiment of the invention is illustrated in'the 21000111.

panying drawings, in which-F Fig. 1 is a vertical axial section through 46 the front portion of the, headstock and spindle, front spindle bearing, chuck, chuck housing and my improved chuck closing and opening mechanism.

Fig. 2 is a plan section, taken on 2-1-2 of Fig. 1. t

- Fig. 3 is a vertical transverse section taken on the line 33 of Fig. 1.

Fig. 4 is a detail front elevation of the split collet. f V Fig. 5 is a fragmentary view of a portion of the split collet, showing in side elevation one of the collet expanding springs.

Referring to the drawings, 10 designates a front endportion of the headstock and 11 the front end portion of the hollow spindle, 12 the front spindle bearing and 13 the usual anti-friction and thrust bearing. In the construction shown, the spindleisdriven by a gear 14 keyedon its forward end, said gear being driven by a pini0n15 (Fig. 3).

Describing the chuck, 16 designates a the line group of long screws 18, one of which is shown in dotted lines in Fig. 1. 19 designates as an entirety the split collet'consisting, in the instance shown, of four quadrant segments between the meeting ends of which are inserted leaf springs. 20, each spring, as shown in Fig. 5, being secured by a screw 21 in a shallow depression 22 in the 3 end of one segment and exerting a thrust on the opposed end of the adjacent segment, whereby the foursprings normally tend to expand the collet. The collet is held from moving outwardly. by an adjusting ring 23 which, as shown in Fig. 1, is screwed into the outer tapped end of the body member 17. The split collet 19 is formed with an outer cylindrical surface whichis tapered, as shown at 24 in; Fig. 1 to fit the tapered bore 25 of a collet closing ring 26 that is slidably fitted. in the bore of the chuck bodj 90 ments corresponding with thecollet segments. These ring segments 28 are known as collet pads, and they are secured in place i wardly to ungripping position, thus leaving on the collet by screws 29 (see Fig. 4). j

Three longitudinal slots 30 are milled 120 apart in the body member 17, and in these slots are mounted on pivot pins 31 a corresponding group of levers each formed with a comparatively long rearwardly extending arm 32 terminating in an outwardly'turned finger 32", a short outwardly extending arm 33, and a short inwardly extending arm 34. Three slots 35 are milled in the outer face of the back plate 16, these slots 35 registering with the slots30, and accommodating the fingers 32 of the arms 32. The inwardly directed arms 34 of these levers engage grooves 36 milled crosswise in the outer surface of the collet closingring 26. From an inspection of Fig. 1 it will be plain that an inward movement imparted to the lever arms 32 will impart to the col.-

let closing ring 26 an outward. or colletclamping movement in an axial direction.

The outer diameters of the back. plate member 16 and the body member 17 are made equal, so that a continuous cylindrical surface is formed on which is slidably fitted a ring 37, hereinafter referred to'as a slider.

This slider is prevented from turning on the body member 17 by a pilot screw 38, the innerend of which slidably fits a longitudinal groove 39in the outer periphery of the-back plate 16.

Three slots aremilled in the rear portion of the inner periphery of the slider 37 and in these slots are fitted hardened steel wedge blocks I 40 secured in place by screws 41.

Thesewedge blocks 40 are in radial align-,

ment with the slots 35 and 30, and the cam or wedge faces of the blocks are adapted to engage the fingers 32' of the lever arms 32, as clearly shownin- Fig. 1, from which it will be seen that a sliding movement in wardly, or to the left, given to the slider 37 will impart an inward radialmovement to the lever arms 32, and in turn will impart a. longitudinal outward or gripping movementto the collet closing ring 26 through engagement of the lever arms 34 with the grooves 36 therein.

Three longitudinal slots 42 in the. inner periphery'of the outer POTiSiOTl Of the slider 37 form clearance spaces for the shortcutwardly extending arms 33 of the collet ring secured by screws 44 in the inner ends of Knockout blocks 43 are these grooves 42; the position of the knock-- out blocks in the grooves being such that toward the end of the outward sliding movement ofv the' slider 37 they will strlke the lever arms '33 after the blocks 40 have cleared the fingers 32 on lever arms 32. Continued outward movement of the slider 37 will then cause the levers to turn in a clockwise direction .viewing Fig. 1, and, through lever arms3'4, positivel move the collet clampingv ring 26 inward y or rearthe collet expanding springs20 free to act and expand the collet and thus release the work held in the latter.

The chuck mechanism thus far described is surrounded bya housingunit comprising? 49. In the front of the housing is a circular j opening 50 concentric with the chuck to rmit application and removal of the wor Sliding movement is given to the slider 37 by means of a forked lever 51, best shown in Fig. 3. .The' forked arms of this lever are fulcrumed on a pair of studs 52 secured in two holes in horizontal alignment in the upper housing member 45. The inner ends of these studs enter holes 53in bosses 54 on the forked lever 51. The lower ends of the forked arms of the lever are formed with bosses 55 that are bored to form bearings for the trunnion portions 56 of two segmental shoes 57 which slidably fit an annular groove 58 (Fig. 1) in the. slider 37 Extending upwardly from the forked arms of lever 51 is a forked stem or lug 59 that is connected by a link 60 (Figs. 1 and 2) to the outer end of a rack bar 61 mounted to slide in a suitable guideway 62 in the upper section .45 of the housing. Rack bar 61 is engaged a... L 1-121. 1...... L.... flunk L'U tile 161.1!- L'lllS 118.5 caused thfi wedge blocks to cam the collet-clamping levers in a direction to advance the collet clampmg rm 26 over the tapered'surface of the collet, rst moving the latter into contact pad 46 is fitted to a horiwardly or to the right. During the first g with the arms 33 of the collet-clamplng removed from the chuck, the hand lever 66 is swung in the op osite direction to shift the rack bar 61 an link 60 inwardly or to the left and this shifts the slider 37 outpart of this movement of the slider, the wedge blocks pass off the fingers 32 of the collet clamping levers, relieving the lever y arms 32 of pressure; Continued movement V of the slider 37 in the same direction brings the knockout blocks 43. into engagement levers, swin 'ng the latter in a clockwise direction an thus positively retracting the collet-clamping ring 26 from the collet, so that the latter is then free to expand under the thrust of its springs 20, releasing the work. I

From the foregoing it will be seen that the device of the present invention provides" a .means for positively actuating the colletclamping ring in both directions, that is, in a direction to compress the collet and grip the work, and in the reverse direction to free the collet permitting it to expand and release the 'work. By adjusting the stop ring 23 inwardly or outwardly, the point in the travel, of the collet-clamping ring at which the clamping or compressing action begins may be'varied to suit slight variations in the diameter of the bar stock held bythe collet. I

, I have herein illustrated and described one physical embodiment of the principle of the invention which in practice has been found to satisfactorily effectuate the stated purpose or object thereof; but I do not limit the invention to the structural details disclosed, ,but reserve such variations, modifications and mechanical equivalents .as fall within the spirit and purvlew of the claims.

I- claim:

1; In a chuck of the type described, the combination of a hollow chuck body, a selfexpandingcollet mounted in said body a collet-clamping ring encircling said col et, 'said collet and clamping ring 'e ing formed with tapered engaging surfaces, a group of levers pivoted in said chuck body each having an arm articulated'with said clamping ring, and a sliding member on said chuc body adapted to rock said levers in both directions.

' 2. In a chuck ofthe type described, the combination of a hollow radially slotted chuck body, a self-expanding collet mounted in said body, a collet-clamping-ring encircling said collet, said collet and clamping 4 ring being formed 1 with tapered engaglng surfaces, a group of levers pivotedln the v slots of said'chuck body, each of said levers having an inwardly extending arm articulated with said clamping and a pairof with the stop rin '23 and then gripping the outwardly directed arms projecting through collet on the worE. When the wor is to be the eriph'ery of said chuck body, a ring slida ly mounted on said chuck body adapted when moved in one direction to engage and rock one of said outwardly directed arms, and when moved in the opposite di rection toengage and rock the other of said outwardly directed arms, andmeans for actuating said last named ring,

.3. In'a chuck of the type described, the combination of a hollow chuck body, a selfexpanding collet'splin ed in said chuck body,

a coIlet-clampingring encircling said collet, said collet and clamping ring being formed with tapered engaging surfaces, a collet stop ring adjustably mounted in the outer end of said chuck body, and manually operable means for moving said clamping ring in both directions lengthwise of said collet.

tions. I

5. In a chuck of the type described, the

combination of a hollow chuck body, a selfexpanding collet mounted in said body, a collet-clamping ring encircling said collet, said collet and clamping ring being formed with tapered engaging-surfaces, a group of levers pivoted in said chuck body each having an inwardly directed arm articulated with said clampmgring and a pair of outwardly directed slidably mounted on said chuck body adapted when moved in one direction to: engage and rock one of said outwardly directed arms projecting through the periphery of said chuck body, a ring ber mounted on said body and articulated with said clamping ring serving, when 'moved in one direction, tocause said clamping ring to compress said collet, 'andiwhen" moved 1n the reverse direction to cause said clamgingring to release said collet.

n -a. chuck of the type described, the j v combination of a hollow chuck body, a selfexpunding collet mounted in said body, a.

collet clamping ring enclrcling said collet said collet and clamping ring bein forme with tapered engaging surfaces, an a group 7 of levers pivoted in said body each having an arm articulated with said clamping ring, said leversserving, when rocked 1n one direction to cause said clamping ring to compress said collet, and when moved; in the reverse direction to cause said clamping ring to release said collet.

GEORGE M. cLAss. 

